This section provides background information related to the present disclosure which is not necessarily prior art.
Traditionally, hot-fill plastic containers, such as polyethylene terephthalate (“PET”), have been commonplace for the packaging of liquid products, such as fruit juices and sports drinks, which must be filled into a container while the liquid is hot to provide for adequate and proper sterilization. Because these plastic containers are normally filled with a hot liquid, the product that occupies the container is commonly referred to as a “hot-fill product” or “hot-fill liquid” and the container is commonly referred to as a “hot-fill container.” During filling of the container, the product is typically dispensed into the container at a temperature of at least 180° F. Immediately after filling, the container is sealed or capped, such as with a threaded cap, and as the product cools to room temperature, such as 72° F., a negative internal pressure or vacuum pressure builds within the sealed container. Although PET containers that are hot-filled have been in use for quite some time, such containers are not without their share of limitations.
One limitation of PET containers is that because such containers receive a hot-filled product and are immediately capped, the container walls contract as a vacuum pressure is created during hot-fill product cooling. Because of this product contraction, hot-fill containers may be equipped with circumferential grooves and vertical columns to aid the container in maintaining much of its as-molded shape, despite the vacuum pressure. Additionally, hot-fill containers may be equipped with vacuum panels to control the inward contraction of the container walls. The vacuum panels are typically located in specific wall areas immediately beside vertical columns and immediately beside circumferential grooves so that the grooves and columns may provide support to the moving, collapsing vacuum panels yet maintain the overall shape of the container.
Hot-fill containers may be molded in a preferred shape, such as a cylindrical shape with a circular cross-section such that any internal vacuum pressure created during the cooling of the hot-fill liquid may equally affect the circular wall. As a result of such cooling, hot-fill containers typically experience a degree of container wall movement that is only mildly detectable to the human eye. In other words, because of the specific, strategic location of a limited number of vacuum panels that account for nearly all vacuum absorption of the container, hot-fill containers may typically maintain their overall shape with no appreciable change in appearance. A limitation of current containers lies in maintaining the general container shape yet permitting controlled deformation of the container during cooling to maintain the overall shape of the container.
What is needed then is a hot-fill container that is capable, upon cooling, of forming into unique and freeform shapes that absorb, in a controlled manner, internal vacuums to a degree and that also generally maintain the overall cylindrical shape of the container.